George Clooney took London's Leicester Square by storm this evening for the premiere of his new film The Monuments Men.

A siege of screaming fans gathered to see the actor, who wrote, directed and stars in the Second World War comedy, inspired by the true story of a team of soldiers on a mission to rescue valuable artwork stolen by the Nazis during the invasion of Europe.

Clooney admitted he managed to have a few laughs on set, despite being the director.

He said: "I've done it a few times now but these guys are fun because they're friends of mine, so I really enjoyed their company."

The Monuments Men were comprised of art historians and architects who were much older than the other soldiers fighting on the frontline.

And though the Hollywood heartthrob confessed he has never seen Dad's Army he admitted he took inspiration from classic war movies.

"We based it on all those old films that we like, like The Great Escape and films like that because we wanted to have a little humour in it too," said Clooney.

Matt Damon, who has worked with Clooney many times before, insisted their friendship made it easier for him to take orders.

Damon explained: "It's actually much easier to be directed by a friend. When you're partnered with somebody whose a friend you cut out all of the diplomacy which really wastes a lot of time.

"There's a whole way you're supposed to speak to each other on film sets or in theatre, and it's all about protecting people's egos. And when you're working with your friend they just say, 'That sucked!'

"There's a baseline of trust that never comes into question, and you solve the problems a lot quicker."

Downton Abbey star Bonneville said he felt "incredibly lucky" to be representing the British in the movie.

"There's only one Brit in it really, in a principal part, and it was really nice of the Americans to let me in," he laughed.

The cast arrived in London after promoting the film in Germany and Italy and head straight to Paris tonight.

John Goodman said the camaraderie on set had been reignited on the tour.

"There's a lot of luggage packing and unpacking, which is always a drag, but it's good to be with the guys again," he said.

But despite all the humour and the fun on set, Bill Murray admitted the reality of war and the atrocities of the Nazi regime was still with them.

He revealed: "We filmed in this mine where they built the V2 rocket, which landed on London, tried to destroy London, and if it had been successful would have destroyed London. And to be there to feel the vibration, just the sense of where we are, this is real here, and we're representing some people that saved the art.

"A lot of art was saved by these men, but the idea that the monster's master plan of destroying all the art, of destroying the other cities and their civilisations didn't take place, it's a blessing."

Cate Blanchett also stars in The Monuments Men, which opens in cinemas on Friday.